With the recent energy saving trends, attention has been paid to commonly available environmental energy that is independent of fossil fuels and the like. Power generation energy based on sunlight, wind power, or the like is widely known as environmental energy. Commonly available vibration energy may be environmental energy having no lower energy density than the above-described types of power generation energy.
Vibration power generators have been developed which generate power utilizing the vibration energy. An electret that can semipermanently retain charge is widely used for such power generators (see, for example, Patent Literatures 1 to 3). This technique provides a power generator utilizing an electret and including a pair of movable substrates disposed opposite each other and reciprocating to generate power, electrets disposed on one of the substrates, and current collecting electrodes disposed on the other substrate to collect charge generated by the action of the electrets on the opposite substrate. Each current collecting electrode in the pair of current collecting electrodes is grounded via a load resistor to which generated power is supplied. The charge collected by the movable substrates is aggregated and supplied to the load via a rectifier.